Mentzer's body was found Sunday by his brother Raymond, also a title-winning competitive bodybuilder, in the apartment they shared in Rolling Hills Estates, said David Rice of L.R. Rice Mortuary in Torrance.

The cause of Mike Mentzer's death was not disclosed, pending a coroner's investigation. He had a history of heart trouble.

After making funeral arrangements for his brother, Ray Mentzer's body was found in bed at the apartment. He was declared dead Monday, about 24 hours after his brother died.

Rice said Ray Mentzer was a dialysis patient who looked "quite distressed'' when he came to make funeral arrangements. His death also was being investigated by the coroner's office, spokesman Scott Carrier said.

In the late 1970s, Michael Mentzer created shock waves in the bodybuilding industry with the notion that six-day-a-week training was unnecessary. He won converts by winning several contests, including first place in the medium weight division at the 1976 Mr. America contest and first in the heavyweight division of the 1979 Mr. Olympia championships.

Born near Philadelphia on Nov. 15, 1951, Mike Mentzer started lifting weights at the age of 11 and competed a year later in his first lifting contest. He later competed in Mr. America, Mr. World, Mr. Universe and Mr. Olympia contests. He placed second overall Mr. Olympia in 1979.

In 1980, he lost the Mr. Olympia contest to Schwarzenegger and stated publicly that he felt he was robbed.

"We may be able to send a man to the moon, but when it comes to recognizing the rightful winner of the 1980 Olympia, mankind is surely arrested in its development,'' Mentzer said later.

Mike's younger brother, Ray, was born on Aug. 2, 1953. In 1978 he won the Mr. USA title and a year later, in 1979, the Mr. America title. Later the same year he placed second in the Mr. Universe competition.

The Mentzer brothers were both single and their parents are deceased.